Bicycle speed change system, bicycle speed change method and bicycle speed change operation assembly

ABSTRACT

The following technical measure is taken to provide a bicycle speed change system or method wherein a speed change operation can be performed substantially without unhanding a handlebar and without erroneously shifting to a lower or higher speed. 
     Specifically, the bicycle speed change system (1) comprises a front speed shifter (1a), a rear speed shifter (1b), and speed change operation assemblies respectively including cylindrical operation members (4a, 4b) rotatably supported around right and left grip portions (3a, 3b), respectively, of a handlebar (2); each of the shifters being operated by a control cable (T) which is pulled or released by rotating a corresponding one of the cylindrical operation members, wherein each of the cylindrical operation members (4a, 4b) is designed so that rotation thereof in a direction of moving its top surface rearward causes a corresponding one of the shifters (1a, 1b) to shift to a lower speed position.

This application is a continuation of application Ser. No. 08/084,281,filed on Jul. 8, 1993.

TITLE OF THE INVENTION

Bicycle Speed Change System, Bicycle Speed Change Method and BicycleSpeed Change Operation Assembly

1. Field of the Invention

The present invention relates to a bicycle speed change system, abicycle speed change method and a bicycle speed change operationassembly, more specifically to those wherein a cylindrical member as aspeed change operation member is rotatably supported around each gripend portion of a handlebar so that a speed change operation can beperformed substantially without unhanding a handlebar and withouterroneously shifting to a lower or higher speed.

2. Background Art

As shown in FIG. 10, a conventional speed change system for a bicycleprovided with a front derailleur a and a rear derailleur b comprises aspeed change operation assembly d1 for the front derailleur and anotherspeed change operation assembly d2 for the rear derailleur. Each of thespeed change operation assemblies is mounted at a suitable portion of abicycle such as a handlebar and connected to a corresponding one of thederailleurs a, b by means of a corresponding control cable c1, c2. Thederailleurs a, b are activated by operating the respective speed changeoperation assemblies d1, d2.

Each of the conventional speed change operation assemblies d1, d2includes a lever having a base portion rotatably supported on a fixedshaft which is mounted on the bicycle frame or handlebar. The controlcable c1, c2 is wound on the base portion of the lever. When the leveris turned in one direction, the control cable c1, c2 is wound further ona cable winding groove of the lever base portion. On the other hand,when the lever is turned in the opposite direction, the control cale c1,c2 is paid out from the winding groove under the tension applied by areturn spring of the derailleur. The axial movement of the control cableis transmitted to the derailleur for actuation.

Such a derailler as shown in FIG. 10 (speed shifter of the externalmounting type) is commonly used for laterally pressing a chain relativeto a sprocket cluster which includes a plurality of diametricallydifferent sprockets arranged side by side at a predetermined spacing,thereby performing a speed change by shifting the chain into engagementwith a desired sprocket.

A rear derailleur, which is provided at the rear wheel, includes a chainguide which rotatably supports a guide pulley and a tension pulley, asdisclosed in the Japanese Patent Application Laid-Open No. 63-251388 forexample. The chain guide is rotatably supported, via a shift linkagemechanism such as a parallelogram pantograph mechanism, on a link basemounted on the bicycle frame while being urged in a chain tensioningdirection. The shift linkage mechanism is deformed by operating a speedchange lever assembly connected to the linkage mechanism via a controlcable, thereby translating the chain guide, which is carried by amovable member of the shift linkage mechanism, axially of the hub shaftto shift the chain into engagement with a desired sprocket of a multiplefreewheel for speed change.

On the other hand, a front derailleur includes a pair of inner and outerguide plates facing each other with the chain interposed therebetween.The pair of guide plates is moved laterally relative to a front gear,which includes a plurality of sprockets arranged side by side, forpressing the chain inward or outward into shifted engagement with adesired sprocket.

The conventional speed change operation assemblies described above areprovided at a suitable portion of the handlebar or bicycle frame and maynecessitate removing the hand from the handlebar at the time ofperforming a speed change. During the speed change operation, therefore,it becomes impossible to apply brake quickly, and steering of thebicycle is unavoidably instable since the bicycle must be steered by asingle hand.

Meanwhile, a speed change operation is required usually when the roadcondition change, for instance, from flat to slope or vice versa. Insuch a case, the running condition tends to become unstable with greaterneeds for braking.

In order to solve this problem, Japanese Utility Model Laid-Open No.58-26693 proposes a so-called rotary-grip type speed change operatingassembly which comprises a cylindrical operation member is supportedaround each grip end portion of a handlebar. The cylindrical operationmember is rotationally operated to pull or release a speed changecontrol cable.

The speed change operation assembly described in the above-mentionedpublication makes it possible to perform a speed change operationwithout unhanding the handlebar. The running safety can be greatlyimproved.

Conventionally, the rear derailleur is designed to move the chain guidelaterally inward for bringing the chain into shifted engagement with alower speed sprocket (larger sprocket) when the control cable is pulled.On the other hand, the front derailleur is designed to move the pair ofguide plates laterally outward for bringing the chain into shiftedengagement with a higher speed sprocket (larger sprocket) when thecontrol cable is pulled.

Therefore, for simultaneously causing both of the front and rearderailleurs to perform a change to a lower speed, it is necessary towind the rear derailleur control cable by the relevant speed changeoperation assembly while paying out the front derailleur control cablefrom the relevant speed change operation assembly. As a result, it isnecessary to turn the respective speed change operation assemblies forthe front and rear derailleurs in the opposite directions forsimultaneously causing both of the front and rear derailleurs to performa change to a lower or higher speed.

However, a serious problem arises if such rotary-grip type speed changeoperation assemblies as disclosed in the above Japanese publication areused in combination with both of the front and rear derailleurs of thebicycle.

Specifically, with the conventional speed change system, the frontderailleur is designed to bring the chain into shifted engagement with ahigher speed sprocket, namely a larger sprocket, when the control cableis pulled, as described previously. On the other hand, the rearderailleur is designed to bring the chain into shifted engagement with alower speed sprocket, namely a larger sprocket, when the control cableis pulled. Thus, it is necessary to turn the respective speed changeoperation assemblies, namely the cylindrical operations membersrotatably supported on the handlebar, in the opposite directions forequally causing both of the front and rear derailleurs to perform achange to a lower speed at an abrupt change of the road condition to asteep uphill for instance.

However, it is an extremely unnatural action for the rider to turn thetwo cylindrical operation members in the opposite directions under thesituation where the road condition is changing. Apparently, the rider'sboth hands gripping the handlebar are subjected to equally directedforces, consequently making it difficult to turn only one of thecylindrical operation members in a direction against the force. As aresult, the rider is likely to erroneously turn both of the cylindricaloperation members in the same direction, thus failing to perform a quickchange to a desired lower speed by causing one derailleur to shift to ahigher speed position.

Especially, with mountain bikes designed for off-road riding, a failurein speed change to follow an abrupt change of the road condition cancause a bicycle overturn due to insufficient transmission of a pedallingforce to the wheel.

DISCLOSURE OF THE INVENTION

It is, therefore, an object of the present invention to provide abicycle speed change system and method wherein a speed change operationcan be performed substantially without unhanding a handlebar and withouterroneously shifting to a lower or higher speed.

Another object of the present invention is to provide a speed changeoperation assembly preferred for such a bicycle speed change system andmethod.

The present invention provides a bicycle speed change system whichcomprises a front speed shifter, a rear speed shifter, and speed changeoperation assemblies respectively including cylindrical operationmembers rotatably supported around right and left grip portions,respectively, of a handlebar, each of the shifters being operated by acontrol cable which is pulled or released by rotating a correspondingone of the cylindrical operation members, characterized in that:

each of the cylindrical operation members is designed so that rotationthereof in a direction of moving its top surface rearward causes acorresponding one of the shifters to shift to a lower speed position.

Other objects, features and advantages of the present invention will beclearly understood from the following description of a preferredembodiment given with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an overall arrangement of a bicycle speedchange system according to the present invention.

FIG. 2 is a plan view showing a right speed change operation assemblyfor controlling a rear speed shifter.

FIG. 3 is a longitudinal sectional view of the speed change operationassembly shown in FIG. 2.

FIG. 4 is a sectional view taken on lines IV--IV in FIG. 3.

FIG. 5 is a sectional view taken on lines V--V in FIG. 3.

FIG. 6 is a view showing the operation of a first ratchet mechanismshown in FIG. 5.

FIG. 7 is a sectional view taken along lines VII--VII in FIG.

FIG. 8 is a plan view showing a left speed change operation assembly forcontrolling a front speed shifter.

FIG. 9 is a sectional view taken on lines IX--IX in FIG. 8.

FIG. 10 is a side view of a bicycle showing the entirety of a bicyclefitted with a conventional speed change system.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment according to the present invention will now be describedin more specific detail referring to FIGS. 1 to 9.

As shown in FIG. 1, a speed change system 1 according to the presentinvention mainly comprises a front shifter or derailleur 1a, a rearshifter or derailleur 1b, and their respective speed change operationassemblies 5a, 5b, which respectively include a correspondingcylindrical operation member 4a, 4b functioning as a speed changeoperation member supported rotatably around a left or right grip endportion 3a, 3b of a handlebar 2.

The front derailleur 1 a according to the embodiment is arranged so thatwhen an inner wire t1 of a control cable T further comprising an outersheath t2 is pulled, a chain is shifted to a higher-speed orgreater-diameter gear.

On the other hand, the rear derailleur 1b is arranged so that the chainis shifted to a lower-speed or greater-diameter gear when the innercable t1 of the control cable T is pulled.

The front and rear derailleurs 1a, 1b are conventional derailleurs andwill not be described here in detail.

Now, the following description will be made primarily for the rightspeed change operation assembly 5b for controlling the rear derailleur1b. The left speed change operation assembly 5a for controlling thefront derailleur 1a has basically the same constitution.

As shown in FIG. 3, the speed change operation assembly 5b according tothe embodiment is integrated with a right brake lever assembly 6b andthe right grip end portion 3b.

At a base end portion of a brake bracket 8 of the brake lever assembly6b, there is provided a cylindrical mounting portion 10 formed with aslit 9 which is a longitudinal cut made to penetrate the circumferentialwall of the bracket. This cylindrical mounting portion 10 is fitted onthe handlebar 2 laterally inwardly of the grip end portion 3b. The slit9 is traversed by a mounting screw 11 which causes the inner diameter ofthe cylindrical mounting portion 10 to shrink elastically, therebyfixing the brake bracket 8 and the speed change operation assembly 5b tothe handlebar 2.

As shown in FIGS. 2 and B, the brake lever assembly 6b according to theembodiment has, in addition to the brake bracket 8 extending forwardlyfrom a front face of the handlebar 2, a brake lever 13 pivotallyconnected at its base end portion to a lever shaft 12 provided on thebrake bracket 8 and extending ahead of a handle grip 7. A brake cable Wcomprises an inner cable w1 and an outer sheath w2. The outer sheath w2is connected to a laterally inner end portion of the brake bracket 8,whereas the inner cable w1 is introduced into an interior space of thebrake bracket 8 and has an end nipple 13a connected to a base endportion of the brake lever 13.

The speed change operation assembly 5b according to the embodimentincludes a cylindrical operation member 4b and a speed change operationmechanism 14. The cylindrical operation member 4b is rotatably supportedlaterally outwardly of the cylindrical mounting portion 10 fixed on thehandlebar 2, namely around the right grip end portion 3b, to becontinuous with a handle grip 7.

The speed change operation mechanism 12 is provided at the cylindricaloperation member 4b and at the base end portion of the brake bracket 8.

The cylindrical operation member 4b according to the embodiment isrotatably supported around a cylindrical sleeve 15 which is fixed aroundthe handlebar 2 axially outwardly of the base end portion of the brakebracket 8.

The cylindrical operation member 4b chiefly includes a control gripportion 16 for the rider to grip and turn, a reel portion 17 arrangedlaterally inwardly of the control grip portion 16 to wind the inner wiret1 of the control cable T, and a pawl housing 28 for accommodating aratchet pawl 29 of a first ratchet mechanism 25 to be described later.

The control grip portion 16 is provided with a rubber coating 19 for therider to grip conveniently, and the coating provides substantialcontinuity with the handle grip 7.

The cylindrical operation member 4b or the handle grip 7 can be grippedfor steering while also enabling a speed change operation.

FIG. 2 is a plan view of the speed change operation assembly 5baccording to the present embodiment. FIG. 3 is an enlarged longitudinalsectional view of the same speed change operation assembly 5b.

According to the embodiment, the outer sheath t2 of the control cable Tis fastened to a fixing bolt 18 provided at the base end portion of thebrake bracket 8. The inner wire t1 is passed on a direction changingreel 20 fixed to an upper wall of the base end portion of the brakebracket 8 for directional change before being wound around the reelwinding portion 17 of the cylindrical operation member 4b.

As shown in FIGS. 2 and 2, the direction changing reel 20 is supportedrotatably on a support shaft 21 which is provided on the upper wall ofthe base end portion of the brake bracket 8. The direction changing reelhas the function of changing the running direction of the inner wire t1of the control cable T. The inner wire extends toward the reel along thehandlebar 2 and is then directed toward the outer circumference of thecylindrical operation member

The inner wire t1 guided by the reel 20 for directional change has anend nipple 22 engaging in a nipple hole 23 provided at a wire windinggroove 17a of the winding reel portion 17 of the cylindrical operationmember 4b. As a result, the inner wire t1 is fixed to the cylindricaloperation member 4b.

As shown in FIGS. 1 and 2, when the right cylindrical operation member4b according to the embodiment is turned to cause its top surface tomove rearward (in the direction indicated by Arrow P), the inner wire t1of the control cable T is pulled. The other end of the inner cable t1 isconnected to the rear derailleur.

Laterally inwardly of the cylindrical operation member 4b is provided aretainer mechanism 22 which regulates the turning movement of thecylindrical operation member 4b.

The first ratchet mechanism 25 is included in the retainer mechanism 22according to the embodiment and functions to hold the cylindricaloperation member 4b at a desired rotational position when thecylindrical operation member 4b pulls the inner wire t1.

The retainer mechanism also includes a resistance generating means 26which imparts friction to prevent the inner wire t1 wound on the windingreel portion 17 of the cylindrical operation member 4b from beingunexpectedly paid out under the tension applied by a return spring ofthe derailleur.

A ratchet wheel 27 as a constituent member of the first ratchetmechanism of the retainer mechanism 22 is provided axially inwardly ofthe cylindrical operation member 4b and around the sleeve 15, as shownin FIG. 3.

The ratchet wheel 27 has an engaging teeth portion 30 formed at alaterally outer portion of the rachet wheel outer circumference, and aresistance imparting portion 31 which gives a predetermined resistanceagainst the cable releasing rotation of the cylindrical operation member4b. The engaging teeth portion 30 engages the ratchet pawl 29 housed inthe pawl housing 28 at the inner end of the cylindrical operation member4b.

As shown in FIG. 5, the engaging teeth portion 30 of the ratchet wheel27 is formed with one-way sloping engaging teeth 32.

As shown in FIG. 6, when the cylindrical operation member 4b is turnedin the cable winding direction (Arrow P), the ratchet pawl 29 housed inthe pawl housing 28 of the cylindrical operation member 4b is liftedradially outward to allow relative movement between the ratchet wheel 27and the cylindrical operation member 4b. On the other hand, when thecylindrical operation member 4b is turned in the cable releasingdirection (Arrow Q), a ring spring 29a elastically urges the ratchetpawl 29 radially inward into engagement with the engaging teeth 32 ofthe ratchet wheel 27, so that the cylindrical operation member 4b turnsintegrally with the ratchet wheel 27, as shown in FIG. 5.

As shown in FIGS. 3 and 7, a ring-form friction band 33 is fitted on theresistance imparting portion 31 of the ratchet wheel 27 to give apredetermined rotational resistance to the ratchet wheel 27. The endportions of the friction band 33 are brought closer to each other by atightening means 50 which includes a tightening bolt 32 and a tighteningnut 35, thereby creating the predetermined rotational resistance for theratchet wheel by causing the friction band to compressively fit on theouter circumferential surface of the resistance imparting portion 31.

As shown in FIG. 7, the friction band 33 of the embodiment, which ismade by pressing a plate spring material into an annular form, has aplurality of arcuate contact portions 33a in slidable contact with theouter circumferential surface of the resistance imparting portion B1.The friction band also includes a plurality of integral joint portions33b formed between the respective contact portions 33a and bulgingradially outward so as not to touch the outer circumferential surface ofthe resistance imparting portion 31, and a parallel pair of tighteningportions 33c extending radially outward from the end portions of theband to be brought closer to each other by the tightening means 50.

Each of the contact portions 33a has an arcuate inner surfacecorresponding to the outer circumferential surface of the resistanceimparting portion 31. Each of the joint portions 33b is larger incurvature than the contact portion 33a to bulge radially outward asspaced from the outer circumferential surface of the resistanceimparting portion 31.

Each of the tightening portions 33c is formed with a perforation 32a,32b through which the tightening bolt 32 of the tightening means 50 isinserted. The tightening bolt 32 is screwed into the tightening nut 35to bring the pair of tightening portions 33c closer to each other.

The tightening portions 33c extend into the interior space of the baseend portion of the brake bracket 8. The tightening portions 33c or thetightening bolt 32 penetrating them contacts the walls of the interiorspace, thereby preventing the friction band from turning with theratchet wheel 27.

Friction is generated between the inner surfaces of the arcuate contactportions 33a and the outer circumferential surface of the resistanceimparting portion 31. As a result, the friction band imparts thepredetermined resistance to the ratchet wheel 27 which is turned withthe cylindrical operation member

The distance between the pair of tightening portions 33c can be adjustedby means of the tightening bolt 32 and the tightening nut 35. It is thuspossible to adjust the tightening force imparted to the resistanceimparting portion 31 by the contact portions 33a, thereby setting therotational resistance to the ratchet wheel at a predetermined value.

The rotational resistance described above should be set, by adjustingthe tightening force provided by the tightening bolt 35 and thetightening nut 35, to overcome the tension applied to the inner wire t1by the return spring of the rear derailleur

The use of the retainer mechanism 22 incorporating the resistancegenerating means 26 of the above-described structure insures smoothoperation of the speed change system 1 according to the presentinvention.

More specifically, the respective contact portions 33a of the frictionband 33 can easily deform elastically due to the presence of the jointportions 33b acting as node points, enabling the friction band to have agreater spring elasticity than was conventionally possible with a simplyannular friction member. As a result, the friction band 33 can be madeto accumulate an elastic energy over the entire circumference thereofwhen the pair of tightening portions 33c are brought closer to eachother by the tightening bolt 32. This means that the tightening portions33c tightened by the tightening bolt 32 and the tightening nut 35 can bemade to have a greater range for adjustment, thereby greatly increasingthe adjustable range of the rotational resistance for the cylindricaloperation member in addition to enabling a fine adjustment.

Further, the joint portions 33b acting as node points also enable thecontact portions 33a to come into uniform pressing contact with theouter circumferential surface of the ratchet wheel 27. Thus, therotational resistance imparted to the ratchet wheel 27 can be stabilizedand optimized, consequently improving the rotational operability of thecylindrical operation member.

Further, the tightening bolt 34 for bringing the tightening portions 33ccloser to each other can be arranged perpendicularly to the axis of thefriction band 33, so that the presence of the tightening bolt will notadd to the axial dimension of the speed change operation assembly.Moreover, the use of the friction band, which is made to slidably fitaround the outer circumferential surface of the ratchet wheel 27, bestsuits the speed change operation assembly of the embodiment wherein thecylindrical operation member 4b is supported on the handlebar.

Further, as shown in FIG. 7, gaps are formed between the joint portions37b and the outer circumferential surface of the resistance impartingportion 31. These gaps can be used for retaining grease to prevent wearbetween the friction band 33 and the resistance imparting portion 31over a long period, thus enabling to maintain the performance of thespeed change operation assembly over a long period.

According to the present embodiment, provision is made of a secondratchet mechanism 36 including an engaging member 20 which is axiallymovable into and out of engagement with the inner end of the ratchetwheel 27, as shown in FIG. 3.

The second ratchet mechanism 36 includes a teeth portion 37 formed atthe inner end surface of the ratchet wheel 27, and a spring 39 housed ina pawl housing hole 38 which is formed in the base end portion of thebrake bracket 8. The engaging member 40 is elastically urged by thespring 39.

The teeth portion 37 is formed with engaging teeth 37a which areopposite in orientation to the engaging teeth 32 of the engaging teethportion 30 of the first ratchet mechanism.

When the cylindrical operation member 4b is turned in the cablereleasing direction, the engaging member 20 of the second ratchetmechanism 36 repetitively comes into and out of engagement with theteeth portion while generating ratcheting sounds. As a result, the ridercan clearly confirm the completion of a speed change operation.

The speed change operation assembly 5b of the above-describedarrangement will now be described with respect to its function.

When the right cylindrical operation member 4b is turned so as to causeits top surface to move rearward (the direction of Arrow P in FIG. 1),the inner wire t1 is pulled by being wound on the-reel portion 17.

At this time, the ratchet pawl 29 held at the axially inner ended of thecylindrical operation member 4b is lifted outward radially of theratchet wheel 27 against the elastic force of the ring spring 29a, asshown in FIG. 6. The ratchet pawl slidably moves relative to theengaging teeth portion 30, so that the resistance imparting portion 31imparts no rotational resistance to the cylindrical operation member 4b.

On the other hand, the ratchet pawl 29 repetitively comes into and outof engagement with the engaging teeth 32 of the ratchet wheel 27 whilegenerating ratcheting sounds in corresponding relation to the teethintervals. As a result, the rider can clearly confirm that a desiredspeed change operation is being performed while also recognizing theextent to which the cylindrical operation member has been turned.

When the rotation of the cylindrical operation member 4b is stopped at adesired rotational position, the tension of the inner wire t1 given bythe return spring of the rear derailleur 1b combined with the elasticforce of the ring spring 29a causes the ratchet pawl 29 to engage theengaging teeth portion 30 with the result that the cylindrical operationmember 4b tends to rotate integrally with the ratchet wheel 27, as shownin FIG. 5. However, such rotation is prevented by the friction generatedby the friction band 33 fitted on the resistance imparting portion 31 ofthe ratchet wheel 27. Therefore, the inner wire t1 is retained at apulled position corresponding to the rotational position of thecylindrical operation member 4b, so that the inner wire t1 is preventedfrom being paid out unexpectedly from a desired position.

Conversely, when the cylindrical operation member 4b is turned so as tocause its top surface to move forward (in the direction of Arrow Q), theratchet pawl 29 is held in engagement with the engaging teeth portion 30to cause the cylindrical operation member 4b to rotate with the ratchetwheel 27. At this time, though the friction band 33 wound on theresistance imparting portion 31 generates a rotational resistance, theforce needed to turn the cylindrical operation member 4b can be renderedonly equal to an amount obtained by subtracting the tension of the innerwire t1 from the rotational resistance of the friction band 33. As aresult, the inner wire t1 can be paid out easily with a reducedrotational force.

With the arrangement described above, the rotational operation of thecylindrical operation member 4b causes the inner wire t1 to be wound upor paid out for performing a speed change. Because of the rotationalresistance given by the friction band 33, the cylindrical operationmember 4b is prevented from turning under the tension of the inner wiret1 applied by the return spring of the rear derailleur 1b, and the innerwire t1 is thereby prevented from being accidentally paid out.

Further, according to the embodiment, since the second ratchet mechanism36 is constituted by the teeth portion 37 at the end surface of theratchet wheel 27 and by the engaging member 20 housed in the pawlhousing hole 38 at the base end portion of the brake bracket, ratchetingsounds are also generated when the inner wire t1 is paid out. Therefore,if the teeth interval of the teeth portion 37 is set to correspond tothe interval between the speed stages, a ratcheting sound can be givenat each of the speed stages. As a result, the rider can perform a speedchange operation very reliably with the help of the ratcheting soundeven when turning the cylindrical operation member 4b in the cablereleasing direction.

The embodiment has so far been described only with respect to the speedchange operation assembly 5b which is mounted at the right hand side ofthe handlebar 2 to control the rear derailleur 1b. Obviously, the speedchange operation assembly 5a mounted at the left hand side of thehandlebar 2 to control the front deraillur 1a employs exactly the samearrangement except for the following points.

Specifically, as shown in FIGS. 8 and 9, the reel 20 of the left speedchange operation assembly 5a is provided on a bottom wall of the brakebracket 8 for pulling and paying out the inner wire t1 under thehandlebar 2.

Thus, when the cylindrical operation member 4a of the left speed changeoperation assembly 5a is turned so as to cause its top surface to moverearward (the direction of Arrow P), the inner wire t1 is paid out. Theopposite rotation (the direction of Arrow Q) results in that the innerwire t1 is pulled.

Though not shown in the drawings, the ratchet pawl for the ratchet wheel27 is oriented oppositely to that for the right ratchet wheel.

With the speed change system 1 according to the embodiment, when theright and left cylindrical operation members 4a, 4b are turned so as tocause their respective top surfaces to move rearward (the direction ofArrow P), the inner wire t1 for the right speed change operationassembly 5b is pulled, whereas the inner wire t1 for the left speedchange operation assembly 5a is paid out.

In addition, the control cable T extending from the right speed changeoperation assembly 5b is connected to the rear derailleur 1b, whereasthe left control cable T is connected to the front derailleur 1a.

Therefore, when the respective cylindrical operation members 4a, 4b areturned rearward (the direction of Arrow P), both of the front and rearderailleurs 1a and 1b are shifted to a lower speed position. Conversely,when the respective cylindrical operation members are turned in theopposite direction (the direction of Arrow Q), both of the derailleursare shifted to a higher speed position.

Such an arrangement eliminates the need for turning the right and leftcylindrical operation members in the mutually opposite directions at thetime of simultaneously causing both derailleurs to shift to a lowerspeed position, as opposed to the conventional speed change system ofthe rotary grip type. Thus, it is possible to reduce the chance ofmoving one derailleur to a lower speed position while moving the otherderailleur to a higher speed position rotating, by erroneously rotatingboth cylindrical operation members in the same direction at the time ofan emergency.

According to the embodiment, both derailleurs 1a, 1b are moved to alower speed positions when the respective cylindrical operation members4a, 4b are equally turned rearward (the direction of Arrow P).

One of the cases where both derailleurs 1a, 1b need be shifted at thesame time to a lower speed position may be when the bicycle begins toclimb a steep uphill slope. In such a case, the rider is generallyrequired to pull the handlebar toward himself/herself for stabilizingthe steering operation and for increasing the pedalling force. At thistime, the rider inherently tends to pull the handlebar towardhimself/herself, causing the grip portions 3a, 3b to turn rearward.

According to the embodiment, the force inherently acting on the gripportions 3a, 3b is utilized for smoothly performing a speed changeoperation. Indeed, the speed change operation does not interfere withthe dynamics of the rider's hands and arms.

In this way, it is possible to perform a speed change operation smoothlyand reliably, thereby assuring comfortable riding. Further, an erroneousoperation of the derailleurs can be effectively prevented to improve theriding safety.

The scope of the present invention is not limited to the above-describedembodiment.

In the embodiment, each of the inner wires is guided by the reel 20 fordirectional change before winding around the corresponding cylindricaloperation member La, Lb. However, the wire may be wound directly aroundthe cylindrical operation member 4a, 4b.

According to the embodiment, the first ratchet mechanism 25 and thesecond ratchet mechanism 36 are provided as retaining means. However,the retaining means may include a friction generating mechanism alone.Further, the present invention is also applicable to a speed changesystem which uses a click mechanism as retaining means.

While the retainer mechanism 24 according to the embodiment is appliedto the speed change operation system incorporating the cylindricaloperation member 4b, it is also applicable independently for example toa speed change operation system which comprises a speed change leverrotatably supported on a lever shaft arranged at a suitable portion of abicycle frame.

Still further, the present invention may be applied not only to speedchange systems of the external mounting type such as front and rearderailleurs but also to other types of speed change systems includingthose of the internal mounting type.

In the second ratchet mechanism employed in the speed change operationassembly according to the embodiment, the teeth portion 37 is formed atthe inner end of the ratchet wheel 27, whereas the engaging member 40 isheld at the base end portion of the brake bracket. However, the teethportion may be formed on the brake bracket, whereas the engaging membermay be retained by the rachet wheel 27.

Similarly to the ratainer mechanism, the second ratchet mechanism, whichis applied to the speed change operation system incorporating thecylindrical operation member 4b according to the embodiment, is alsoapplicable independently for example to a speed change operation systemwhich comprises a speed change lever rotatably supported on a levershaft arranged at a suitable portion of a bicycle frame.

We claim:
 1. A bicycle speed change operation assembly comprising:acylindrical operation member rotatably supported coaxially around a gripend portion of a handlebar; a winding reel arranged coaxially around thegrip end portion for rotation with the cylindrical operation member;cable means connected to the winding reel and a speed shifter, the cablemeans being pulled or paid out by the winding reel for operating thespeed shifter in response to the rotation of the cylindrical operationmember; and a direction changing reel that is supported for rotationabout a support shaft extending perpendicularly to the handlebar fordirecting the cable means, which approaches the direction changing reelin a direction along the handlebar, transversely toward the handlebarfor connection to the winding reel.
 2. The bicycle speed changeoperation assembly according to claim 1, wherein the support shaft ofthe direction changing reel is fixed to a brake bracket of a brake leverassembly.
 3. The bicycle speed change operation assembly according toclaim 1, wherein the winding reel is positioned at an axially inner endof the cylindrical operation member.
 4. A combination of a bicycle brakelever assembly and a bicycle speed change operation assembly, the brakelever assembly comprising: a brake bracket having a cylindrical mountingportion fixed around a handlebar adjacent to a grip end portion thereof;and a brake lever pivotally connected to the brake bracket; wherein thespeed change operation assembly comprises:a cylindrical sleeve fixedcoaxially around the grip end portion of the handlebar and extendinginto the cylindrical mounting portion of the brake bracket; acylindrical operation member rotatably supported coaxially around thecylindrical sleeve; a winding reel arranged coaxially around thecylindrical sleeve at an axially inner end of the cylindrical operationmember for rotation therewith; cable means connected to the winding reeland a speed shifter, the cable means being pulled or paid out by thewinding reel for operation the speed shifter in response to the rotationof the cylindrical operation member; and a retainer mechanism arrangedcoaxially around the cylindrical sleeve and in the cylindrical mountingportion of the brake bracket for rotationally retaining the winding reelagainst a tension applied to the cable means.